At present, ICSI (intra-cytoplasmic sperm injection) is widely used as a micro-insemination method. In micro-insemination, a sperm is selected using a modulation contrast viewing method (see Patent Document 1, for example), and a sperm having satisfactory motility and morphology is injected into an ovum. However, recent advances in IVF (in-vitro fertilization) research have shown statistically that such factors as the presence, size, and number of vacuoles in the sperm head are significantly related to the IVF success rate, but vacuoles in the sperm head are difficult to view by the modulation contrast viewing method used for conventional ICSI. Therefore, a microscope system has been proposed for enabling IMSI (intra-cytoplasmic morphologically selected sperm injection, which is a micro-insemination method in which a sperm is selected under high magnification), in which micro-insemination is performed after selection by detailed viewing of the inside of the sperm head, to be performed in addition to the conventional ICSI. For example, a configuration is adopted in which the modulation contrast viewing method used in ICSI is employed jointly with a differential interference viewing method (see Patent Documents 2 and 3, for example) through a high-magnification objective that is used in IMSI.    Patent Document 1: Japanese Laid-open Patent Publication No. S51-128548    Patent Document 2: Japanese Patent No. 3456252    Patent Document 3: Japanese Patent No. 3415294